This invention relates to apparatus and methods used to harvest a generally cylindrical shaped tissue structure from the body of a patient. More particularly, the invention is directed to an apparatus and method for harvesting a section of a blood vessel from a patient.
In certain circumstances it is desirable to remove sections of tubular tissue structure from a patient""s body. Such tissue may be used in another part of the patient""s body, may be transplanted into a second patient""s body or may be discarded. As used herein, the term xe2x80x9ctubular tissue structurexe2x80x9d includes blood vessels, tendons, bile ducts and any other similar tissue formation which is generally tubular in structure and capable of being separated from surrounding tissue. Although the invention herein will be discussed in terms of harvesting blood vessels it should be understood that the apparatus and method described are equally applicable to harvesting other tubular tissue structure.
Vein harvesting is commonly done in connection with coronary artery bypass surgery. The saphenous vein is a subcutaneous vein which is often used for coronary artery bypass grafting, infra-inguinal bypass grafting and vein-vein bypass grafting. Other veins may also be used including the mammary vessel and the lessor saphenous vein. Previously, it has been necessary to make an incision along the full length of the vein section to be removed. The vein is then freed by severing and ligating the branches of the vein, after which the section of the vein can be removed from the patient. The full length incision must then be closed, for example by suturing or stapling. Obviously, the harvesting of the vein in this manner leaves disfiguring scars which are cosmetically undesirable. Additionally, the large incision creates a risk of infection to the patient and may not heal properly, especially with those patient""s who have poor circulation in their extremities. Such an incision may create a chronic wound which will not heal.
Devices for harvesting a section of a blood vessel without creating a full length incision have been suggested. U.S. Pat. No. 4,793,346 to Mindich discloses a device for harvesting a section of a blood vessel by making only small incisions at opposite ends of the blood vessel section. The device includes a guide rod which fit""s inside of the vein section and a tube having an inner diameter slightly larger than the outer diameter of the vein section to be harvested. The tube has one or more knife blades at the leading edge which are connected to an electrical supply. The vein section is removed by making the incision sufficiently deep so as to expose the ends of the blood vessel to be harvested. The blood vessel is cut to expose one end, the guide rod is inserted inside the blood vessel section, and the tube is placed over the end of the blood vessel section to be removed. The tube is then pushed along the blood vessel (into the patient) while rotating the tube to sever the branches of the blood vessel with the knife blade mounted at the leading edge of the tube. Electrical current is supplied to the knife blades to heat the blades and thereby cauterize the ends of the severed branches of the blood vessel. The procedure is continued until the tube has reached the second of the two incisions. The blood vessel is exposed and cut from the patient at the second incision. The tube is then removed from the patient with the blood vessel section inside of the tube. The blood vessel section is then removed from the tube for further treatment and use as desired.
UK patent application GB 20 82 459A discloses a device for harvesting a section of a blood vessel similar to that disclosed in the Mindich patent. Again, two incisions are made, one at each end of the blood vessel section to be harvested. A guide rod is inserted into the blood vessel section through one of the incisions and a tube having a cutting element having a cutting tool at it""s operative end is passed over the blood vessel section and guide rod assembly. The tube is rotated as it passes over the blood vessel section to sever the connecting branches. After the tube has passed the entire length of the blood vessel section, the section is cut away through the second incision and the tube is removed from the patient with the harvested section inside the tube.
Blood vessel harvesting devices of this type have certain distinct disadvantages. While they eliminate the need for a full length incision to remove the blood vessel segment, two incisions, one at each end of the segment to be harvested, are required in order to remove the blood vessel segment. For patient""s likely to develop chronic wounds, each additional incision increases the risk to the patient, and it is desirable to keep such incisions as close to the patient""s trunk as possible and to minimize the number and size of such incisions. Additionally, such devices are unable to adequately close off several branches of the blood vessel and thus are unable to adequately control bleeding. As a result, the patient suffers greater blood loss than is necessary. These prior devices may also remove more tissue than is necessary because the size of the cutting device is not readily adaptable to the changes in the size of the blood vessel.
In U.S. Pat. No. 5,373,840 to Knighton an improved device and method for vein removal is disclosed which solves some of the problems associated with the use of prior art devices. Knighton discloses an endoscope having a lumen extending longitudinally through the scope body. The endoscope includes means for viewing an area adjacent the distal end of the lumen. The lumen has a lateral dimension large enough to accommodate the blood vessel being harvested and at least one tool for use in harvesting the blood vessel. A first end of the blood vessel section to be harvested is exposed through an incision in the patient""s body. A dissecting tool and a gripping tool are inserted through the lumen of the endoscope and used to dissect the blood vessel away from the surrounding connective tissue of the patient""s body. Additional tools are provided for use through the lumen of the endoscope to remove body fluids and coagulate bleeding tissue, to ligate and sever side branches from the blood vessel to be harvested, and to ligate and sever a distal end of the blood vessel to be harvested when a desired length of blood vessel has been dissected. Only a small incision in the patient""s body is necessary to harvest a relatively long length of blood vessel in a precise and controlled manner using this device and procedure.
Although the ""840 patent to Knighton constitutes a significant improvement in devices and techniques for vein harvesting, it""s multiple tools require more than one operator to complete the procedure. Additionally, it""s single lumen design requires that the vein be contained within the same lumen as the various tools which are used during the dissection procedure. This makes it possible for the vessel to be damaged during the dissection process by the tools which share the same lumen. It is critical that the segment of blood vessel being harvested is handled with great care since it is destined for reuse (as in arterial bypass). Therefore, it is desirable to isolate the vessel as much as possible from the tools which are used in the dissection.
There is a need for a device and method for vein removal which allows a vein to be harvested in an efficient and safe manner from the body of the patient. Specifically, it would be desirable to provide a device which can be effectively operated by a single operator/physician while at the same time protecting the segment of the vessel being removed from the tools which are used in the procedure.
In accordance with the present invention there is disclosed a device for removing a generally cylindrical tissue structure from a patient""s body. The tissue structure may be a blood vessel, bile duct, tendon or other similar cylindrical/tubular tissue structure which may be removed and/or reused in the patient""s body or another patient""s body. The device includes an elongated body portion having distal and proximal ends and at least one lumen extending longitudinally therethrough. The lumen is sized to accommodate the tissue structure and at least one tool used in removing the tissue structure. Means is provided for isolating the tissue structure from the tools used in removing the tissue structure in order to protect the tissue structure from damage. The device may include viewing means to enable the operator to remotely view an area adjacent the distal end of the body portion.
The lumen of the body portion may comprise separate vessel and working lumens, the vessel lumen being sized to accommodate the vessel or similar tubular or cylindrical tissue structure and the working lumen or lumens being sized to accommodate the tools used in the removal procedure. The separation of the vessel lumen and working lumens protects the vessel from the tools used in the procedure. Alternatively, the lumen may comprise a single lumen which includes a section which accommodates the vessel and a working section which accommodates the tools.
The vein harvesting device includes means for detachable connection to the vessel. The connection means may comprise an alligator clip like structure which is connected at its proximal end to a tension means which maintains tension on the connection means and hence the vessel in the direction of the proximal end of the body portion when the connection means is connected to the vessel. A housing is provided through which a body portion may be advanced or retracted through the body portion by the operator controlling an advancement means.
The device may include one or more tools sized so that it may be accommodated within the lumen. The tool has a distal operative tip which may be used to cut a side branch of the vessel, cut the vessel, apply a ligation clip to a side branch of the vessel, apply a ligation clip to the vessel, or remove a patient""s body fluids.
The device includes means for dissecting the vessel from surrounding tissue. The dissection means may comprise a generally cylindrical structure having a length at least as great as the lumen extending through the body portion. The cylindrical shape defines a lumen which is sized to accommodate the vessel which is drawn into the lumen of the dissection means as the vessel is dissected from surrounding tissue. The dissection means is sized to be accommodated within the vessel lumen. The device includes means for advancing or retracting the dissection means through the lumen.
The invention also includes a method of removing a section of generally cylindrical tissue structure such as a blood vessel from a patient""s body. The method includes providing a device having an elongated body portion having distal and proximal ends and at least one lumen extending longitudinally therethrough. The lumen is sized to accommodate the tubular tissue structure and at least one tool used in removing the tissue structure.
A first end of the tubular tissue structure section to be harvested is exposed through an incision in the patient""s body. A gripping tool is inserted through the lumen and the first end of the tissue structure is gripped with the tool. The surrounding tissue is dissected away from the tubular tissue structure with a dissecting element. During the procedure the body portion and the dissecting element are advanced along the tubular tissue structure until a desired length of tissue structure is reached such that the dissected portion of the tissue structure extends into the lumen. During the dissection process the tubular tissue structure is isolated from the tools used in removing the tissue structure except at the distal end of the body portion where the dissection procedure is performed. When the desired length of the tissue structure is reached, the tissue structure is cut at its distal end with a transecting tool which may be inserted through the lumen. Alternatively, a second incision can be made through which the distal end of the tissue structure may be cut.
Where the tissue structure being harvested is a blood vessel, the method may further include advancing the body portion and a dissecting element along the vessel until a side branch of the vessel in encountered. A ligation member is then applied to the branch and the branch is cut between the vessel and the ligation member with a ligating-cutting tool inserted through the lumen. The method may also include controlling bleeding as necessary with a bleeding control tool inserted through the second lumen. In one embodiment the method includes providing a viewing element to enable viewing of the vein dissection in progress. In a further embodiment the method includes maintaining tension on the gripping tool in the direction of the proximal end of the body portion such that tension on the vessel is maintained during dissection.